Features and trends of marine heat waves and marine cold spells along the Western Iberian Coast from four decades of satellite data

Marine Heat Waves (MHWs) have been the focus of numerous studies due to the dramatic consequences they can have on coastal systems. However, Marine Cold Spells (MCSs) can also have harmful effects on the environment while play an important role in the context of global warming. Yet, there is lack of information on the physical attributes and long-term changes of MCSs. This study aims to investigate and compare the features and patterns of both MHWs and MCSs along the Western Iberian Coast (WIC) and its estuaries using satellite-derived Sea Surface Temperatures between 1982 and 2022. Overall, the WIC registered more MCSs than MHWs, although with lower intensities. The coastal region between Minho and Douro Estuaries and Cape São Vicente were favorable for MCSs development. The coastal regions of Minho through Aveiro and the south coast of Portugal registered MCSs and MHWs with the highest average and maximum intensities. No significant trends were observed for MHWs and MCSs features throughout the WIC. MHWs (MCSs) events were found to have been increasing (decreasing) offshore. However, an increase was registered near the coastline for MCS (0.06 events/year). Increased seasonal upwelling could be contributing to mask the development of MHWs and enhance MCSs.